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Georgeann McGuinness

Publications and source records attributed to Georgeann McGuinness.

13 recordsLinked to original sources
PubMed2006

Advantages of parallel imaging in conjunction with hyperpolarized helium--a new approach to MRI of the lung.

Hyperpolarized helium (3He) gas MRI has the potential to assess pulmonary function. The non-equilibrium state of hyperpolarized 3He results in the continual depletion of the signal level over the course of excitations. Under non-equilibrium conditions the relationship between the signal-to-noise ratio (SNR) and the number of excitations significantly deviates from that established in the equilibrium state. In many circumstances the SNR increases or remains the same when the number of data acquisitions decreases. This provides a unique opportunity for performing parallel MRI in such a way that both the temporal and spatial resolution will increase without the conventional decrease in the SNR. In this study an analytical relationship between the SNR and the number of excitations for any flip angle was developed. Second, the point-spread function (PSF) was utilized to quantitatively demonstrate the unconventional SNR behavior for parallel imaging in hyperpolarized gas MRI. Third, a 24-channel (24ch) receive and two-channel (2ch) transmit phased-array system was developed to experimentally prove the theoretical predictions with 3He MRI. The in vivo experimental results prove that significant temporal resolution can be gained without the usual SNR loss in an equilibrium system, and that the entire lung can be scanned within one breath-hold (approximately 13 s) by applying parallel imaging to 3D data acquisition.

Administration, Inhalation↗
PubMed2006

Diffusional kurtosis imaging in the lung using hyperpolarized 3He.

Diseases of the small airspaces represent an increasingly important health problem. Asthma is primarily a disease of airway dysfunction, while chronic obstructive pulmonary disease (COPD) is associated with abnormalities in both the small airways and the alveoli. Conventional diffusion magnetic resonance imaging (MRI) of hyperpolarized noble gases, because of the short T(2)* of the gas, is only capable of monitoring diffusion over short times and hence only short distances. Diffusion imaging is therefore only sensitive to changes in small structures of the lung (primarily the alveoli), and will not adequately interrogate diffusion along the longitudinal axes of bronchi and bronchioles. In this communication we present a new method, termed diffusional kurtosis imaging (DKI), that is particularly sensitive to diffusion over longer distances. DKI may therefore be more sensitive to abnormalities in the bronchioles and bronchi than conventional diffusion imaging. Preliminary DKI measurements on healthy human subjects and one patient with symptoms suggestive of small airway disease are presented. Although the apparent diffusion coefficient (ADC) in the patient was similar to that in the normal controls, diffusional kurtosis was markedly reduced. This suggests that DKI measurements may be useful for assessing diseases of the small airways.

Artifacts↗
PubMed2004

CT screening for lung cancer: suspiciousness of nodules according to size on baseline scans.

PURPOSE: To assess the frequency with which a particular, possibly optimal work-up of noncalcified nodules less than 5.0 mm in diameter identified on initial computed tomographic (CT) images at baseline screening leads to a diagnosis of malignancy prior to first annual repeat screening, compared with a possibly optimal work-up of larger nodules. MATERIALS AND METHODS: Two series of baseline CT screenings in high-risk people were retrospectively reviewed. The first series (n = 1,000) was performed in 1993-1998; the second (n = 1,897), in 1999-2002. In each series, cases in which the largest noncalcified nodule detected was less than 5.0 mm in diameter and those in which it was 5.0-9 mm were reviewed to determine whether diagnostic work-up prior to first annual repeat screening showed or would have shown nodule growth and led or would have led to a diagnosis based on biopsy or surgical specimens. RESULTS: The frequency with which malignancy was or could have been diagnosed when the largest noncalcified nodule was less than 5.0 mm in diameter was 0 of 378, whereas when the largest noncalcified nodule was 5.0-9 mm in diameter, the frequency was 13 or 14 of 238. If persons with only nodules smaller than 5.0 mm had merely been referred for first annual repeat screening without immediate further work-up, the referrals for such work-up would have been reduced by 54% (from 817 [28%] to 385 [13%] of 2,897). CONCLUSION: In modern CT screening for lung cancer at baseline, detected noncalcified nodules smaller than 5.0 mm in diameter do not justify immediate work-up but only annual repeat screening to determine whether interim growth has occurred.

Adult↗
PubMed2003

Wavelet compression of low-dose chest CT data: effect on lung nodule detection.

PURPOSE: To assess the effect of using a lossy Joint Photographic Experts Group standard for wavelet image compression, JPEG2000, on pulmonary nodule detection at low-dose computed tomography (CT). MATERIALS AND METHODS: One hundred sets of lung CT data ("cases") were compressed to 30:1, 20:1, and 10:1 levels by using a wavelet-based JPEG2000 method, resulting in 400 test cases. Each case consisted of nine 1.25-mm sections that had been obtained with 20-40 mAs. Four thoracic radiologists independently interpreted the test case images. Performance was measured by using area under the receiver operating characteristic (ROC) curve (Az) and conventional sensitivity and specificity analyses. RESULTS: There were 51 cases with and 49 without lung nodules. Az values were 0.984, 0.988, 0.972, 0.921, respectively, for original and 10:1, 20:1, and 30:1 compressed images. Az values decreased significantly at 30:1 (P =.014) but not at 10:1 compression, with a trend toward significant decrease at 20:1 (P =.051). Specificity values were unaffected by compression (>98.0% at all compression levels). Sensitivity values were 86.3% (176 of 204 test cases with nodules), 77.9% (159 of 204 cases), 76.5% (156 of 204 cases), and 70.1% (143 of 204 cases), respectively, for original and 10:1, 20:1, and 30:1 compressed images. Results of logistic regression model analysis confirmed the significant effects of compression rate and nodule attenuation, size, and location on sensitivity (P <.05). CONCLUSION: While no reduction in nodule detection at 10:1 compression levels was demonstrated by using ROC analysis, a significant decrease in sensitivity was identified. Further investigation is needed before widespread use of image compression technology in low-dose chest CT can be recommended.

Humans↗
PubMed2003

Small pulmonary nodules: volume measurement at chest CT--phantom study.

Three-dimensional methods for quantifying pulmonary nodule volume at computed tomography (CT) and the effect of imaging variables were studied by using a realistic phantom. Two fixed-threshold methods, a partial-volume method (PVM) and a variable method, were used to calculate volumes of 40 plastic nodules (largest dimension, <5 mm: 20 nodules with solid attenuation and 20 with ground-glass attenuation) of known volume. Tube current times (20 and 120 mAs), reconstruction algorithms (high and low frequency), and nodule characteristics were studied. Higher precision was associated with use of a PVM with predetermined pure nodule attenuation, high-frequency algorithm, and diagnostic CT technique (120 mAs). A PVM is promising for volume quantification and follow-up of nodules.

Algorithms↗
PubMed2002

Acute eosinophilic pneumonia in a New York City firefighter exposed to World Trade Center dust.

We report a sentinel case of acute eosinophilic pneumonia in a firefighter exposed to high concentrations of World Trade Center dust during the rescue effort from September 11 to 24. The firefighter presented with a Pa(O2) of 53 mm Hg and responded to oxygen and corticosteroids. Computed tomography scan showed patchy ground glass density, thickened bronchial walls, and bilateral pleural effusions. Bronchoalveolar lavage recovered 70% eosinophils, with only 1% eosinophils in peripheral blood. Eosinophils were not degranulated and increased levels of interleukin-5 were measured in bronchoalveolar lavage and serum. Mineralogic analysis counted 305 commercial asbestos fibers/10(6) macrophages including those with high aspect ratios, and significant quantities of fly ash and degraded fibrous glass. Acute eosinophilic pneumonia is a rare consequence of acute high dust exposure. World Trade Center dust consists of large particle-size silicates, but fly ash and asbestos fibers may be found in bronchoalveolar lavage cells.

Acute Disease↗
PubMed2002

Cough and bronchial responsiveness in firefighters at the World Trade Center site.

BACKGROUND: Workers from the Fire Department of New York City were exposed to a variety of inhaled materials during and after the collapse of the World Trade Center. We evaluated clinical features in a series of 332 firefighters in whom severe cough developed after exposure and the prevalence and severity of bronchial hyperreactivity in firefighters without severe cough classified according to the level of exposure. METHODS: "World Trade Center cough" was defined as a persistent cough that developed after exposure to the site and was accompanied by respiratory symptoms severe enough to require medical leave for at least four weeks. Evaluation of exposed firefighters included completion of a standard questionnaire, spirometry, airway-responsiveness testing, and chest imaging. RESULTS: In the first six months after September 11, 2001, World Trade Center cough occurred in 128 of 1636 firefighters with a high level of exposure (8 percent), 187 of 6958 with a moderate level of exposure (3 percent), and 17 of 1320 with a low level of exposure (1 percent). In addition, 95 percent had symptoms of dyspnea, 87 percent had gastroesophageal reflux disease, and 54 percent had nasal congestion. Of those tested before treatment of World Trade Center cough, 63 percent of firefighters (149 of 237) had a response to a bronchodilator and 24 percent (9 of 37) had bronchial hyperreactivity. Chest radiographs were unchanged from precollapse findings in 319 of the 332 with World Trade Center cough. Among the cohort without severe cough, bronchial hyperreactivity was present in 77 firefighters with a high level of exposure (23 percent) and 26 with a moderate level of exposure (8 percent). CONCLUSIONS: Intense, short-term exposure to materials generated during the collapse of the World Trade Center was associated with bronchial responsiveness and the development of cough. Clinical and physiological severity was related to the intensity of exposure.

Adult↗
PubMed2002

CT of airways disease and bronchiectasis.

High-resolution CT is accepted as an accurate noninvasive means of diagnosing bronchiectasis. A wide spectrum of abnormalities may be identified at HRCT in patients with airway disease, including various distinctive patterns of bronchiectasis in specific clinical settings, such as ABPA, MAC infection, AIDS, and CF. Characteristic CT findings occasionally suggest a specific diagnosis that may not have been under clinical consideration. HRCT also provides significant clinical use in assessing the degree and extent of airway disease, and allows noninvasive monitoring of disease progression, regression, or response to therapy.

AIDS-Related Opportunistic Infections↗
PubMed2002

Tumor localization and image registration of F-18 FDG coincidence detection scans with computed tomographic scans.

PURPOSE: The aim of this study was to determine the feasibility of registering routine clinical F-18 fluorodeoxyglucose (FDG) coincidence detection (CD) scans with computed tomographic (CT) scans for radiation treatment planning and case management. METHODS: F-18 FDG CD and chest CT scans, performed in 10 randomly selected patients with confirmed or possible adenocarcinoma of the lung, were evaluated. The quality of the matches was verified by comparisons of the center-to-center distance between a region of interest (ROI) manually drawn on the CT slice and warped onto the CD slice with an ROI drawn manually directly on the CD slice. In addition, the overlap between the two ROIs was calculated. RESULTS: All 10 F-18 FDG CD and CT scans were registered with good superimposition of soft tissue density on increased radionuclide activity. The center-to-center distance between the ROIs ranged from 0.29 mm to 8.08 mm, with an average center-to-center distance of 3.89 mm +/- 2.42 mm (0.69 pixels +/- 0.34 pixels). The ROI overlap ranged from 77% to 99%, with an average of 90% +/- 5.6%. CONCLUSIONS: Although the use of F-18 FDG CD shows great promise for the identification of tumors, it shares the same drawbacks as those associated with radiolabeled monoclonal antibody SPECT and ligand-based positron emission tomographic scans in that anatomic markers are limited. This study shows that image registration is feasible and may improve the clinical relevance of CD images.

Adenocarcinoma↗
PubMed2002

CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules.

OBJECTIVE: In the Early Lung Cancer Action Project (ELCAP), we found not only solid but also part-solid and nonsolid nodules in patients at both baseline and repeat CT screening for lung cancer. We report the frequency and significance of part-solid and nonsolid nodules in comparison with solid nodules. MATERIALS AND METHODS: We reviewed all instances of a positive finding in patients at baseline (from one to six noncalcified nodules) and annual repeat screenings (from one to six newly detected noncalcified nodules with interim growth) to classify each of the nodules as solid, part-solid, or nonsolid. We defined a solid nodule as a nodule that completely obscures the entire lung parenchyma within it. Part-solid nodules are those having sections that are solid in this sense, and nonsolid nodules are those with no solid parts. Chi-square statistics were used to test for differences in the malignancy rates. RESULTS: Among the 233 instances of positive results at baseline screening, 44 (19%) involved a part-solid or nonsolid largest nodule (16 part-solid and 28 nonsolid). Among these 44 cases of positive findings, malignancy was diagnosed in 15 (34%) as opposed to a 7% malignancy rate for solid nodules (p = 0.000001). The malignancy rate for part-solid nodules was 63% (10/16), and the rate for nonsolid nodules was 18% (5/28). Even after standardizing for nodule size, the malignancy rate was significantly higher for part-solid nodules than for either solid ones (p = 0.004) or nonsolid ones (p = 0.03). The malignancy type in the part-solid or nonsolid nodules was predominantly bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar features, contrasting with other subtypes of adenocarcinoma found in the solid nodules (p = 0.0001). At annual repeat screenings, only 30 instances of positive test results have been obtained; seven of these involved part-solid or nonsolid nodules. CONCLUSION: In CT screening for lung cancer, the detected nodule commonly is either only part-solid or nonsolid, but such a nodule is more likely to be malignant than a solid one, even when nodule size is taken into account.

Aged↗
PubMedDate not supplied

CT screening for lung cancer Assessing a regimen's diagnostic performance.

PURPOSE: The purpose of this study was to characterize the diagnostic performance of a regimen of CT screening for lung cancer. METHODS: Using a common protocol/regimen of screening, 2968 asymptomatic persons at high risk for lung cancer were enrolled in two studies [Early Lung Cancer Action Projects (ELCAP) I and II] for baseline and annual repeat screening. A total of 4538 annual repeat screenings were performed. The regimen's diagnostic performance was characterized in terms of frequency of positive result of the initial CT as well as of screen-diagnosis and Stage I screen-diagnosis among all diagnoses (interim-diagnoses included), all separately for baseline and annual repeat screenings. RESULTS: The proportions with positive result of the initial CT were 12% and 6% in the baseline and repeat screenings, respectively. The proportions of screen-diagnoses among all diagnoses (interim-diagnoses included) were 97% and 99% in the baseline and repeat cycles, respectively. The corresponding proportions of pre-surgical Stage I screen-diagnoses were 95% and 93%. CONCLUSION: The performance of the ELCAP regimen is quite satisfactory in avoiding over many positive results of the initial CT, and it produces highly promising diagnostic results as for the attainment of cure by early intervention.

Aged↗